Authors : C. Keza; N. Mariita; A. Mwangi; J. C. Niyonzima; N. Nsengiyumva

Volume/Issue : Volume 10 - 2025, Issue 1 - January

Google Scholar : https://tinyurl.com/34ehems9

Scribd : https://tinyurl.com/39jmkkrw

DOI : https://doi.org/10.5281/zenodo.14890823

Abstract : The geothermal energy sector in Burundi has not yet had any particular attention in term of developing this renewable resource which has the potential as a source for electricity generation and direct use applications. The country has more than 13 geothermal springs spread over different regions. This research is focused on the characterization of geothermal reservoir of Mugara and Ruhwa sites. Geophysical and geochemical methods have been used to collect the data. Thus, geological, electrical resistivity data based to Schlumberger method and chemical elements were analysed in order to investigate the geological structures and the quality of these geothermal reservoirs. The results showed that in Mugara site, the geothermal reservoir is located geologically in the spongoliths, coarse cemented sands, clay-sandstone spongoliths whereas the Ruhwa site is found in the white quartzites with intercalations of phyllite rocks with the presence of schites, psammoshistose, sandstone-silty quartzites. The aquifer in Mugara site is a semi-confined aquifer and the Ruhwa geothermal reservoir is a confined aquifer due to its roof, which is composed of clay. The highest temperature in Ruhwa site is 68°c and underground source temperatures are postulated to be as high as 110-120°c based on the quartz geothermometer in the hot springs from the porous sediments. The chemical analysis results of water from Ruhwa and Mugara indicated that 3 elements which are Fe, Mg and K have a high content of 21.5 mg/l, 10mg/l and 76mg/l respectively.

Keywords : Geothermal Reservoir, Burundi, Resistivity, Geology, Ruhwa, Mugara.

References :

1. Aydin, H., & Temizel, C. (2022). Characterization of Geothermal Reservoirs. Accessed on April 17th 2022.  
2. Bakundukize, C. (2012). Hydrogeological and hydrogeochemical investigation of a Precambrian basement aquifer in Bugesera Region (Burundi). Ghent University,
3. Belgique, S. r. d. b. d. (2004). Belgian Journal of Botany: Bulletin de la Société Royale de Botanique de Belgique : Royal Botanical Society of Belgium.
4. Bignall, G., Milicich, S. D., Ramírez, E., Rosenberg, M. D., Kilgour, G., & Rae, A. (2010). Geology of the Wairakei-Tauhara Geothermal System, New Zealand.
5. Björnsson, A. (2005). Development of Thought on the Nature of Geothermal Fields in Iceland from Medieval Times to the Present. Accessed on december 9th 2024.
6. Brace, W., & Orange, A. S. J. J. o. G. r. (1968). Further studies of the effects of pressure on electrical resistivity of rocks. 73(16), 5407-5420.
7. Caldwell, G., Pearson, C., & Zayadi, H. (1986). Resistivity of rocks in geothermal systems: a laboratory study. Paper presented at the proceedings 8th NZ geothermal workshop.
8. Castañeda, D., Brunkal, H., & Class, G. E. J. G. E. C., Colorado School of Mines. (2009). Geophysical Techniques for Geothermal Exploration of Rico, CO.
9. Domra K. J., Djongyang, N., Danwe, R., Njandjock Nouck, P., & Abdouramani, D. (2015). A review of geophysical methods for geothermal exploration. Renewable and Sustainable Energy Reviews, 44, 87-95. doi:https://doi.org/10.1016/j.rser.2014.12.026
10. El-Qady, G. (2006). Exploration of a geothermal reservoir using geoelectrical resistivity inversion: case study at Hammam Mousa, Sinai, Egypt. Journal of Geophysics and Engineering, 3(2), 114-121. doi:10.1088/1742-2132/3/2/002 %J Journal of Geophysics and Engineering
11. Feng, R., Balling, N., & Grana, D. (2020). Lithofacies classification of a geothermal reservoir in Denmark and its facies-dependent porosity estimation from seismic inversion. Geothermics, 87. doi:10.1016/j.geothermics.2020.101854
12. Fournier, R. O., & Rowe, J. J. (1966). Estimation of underground temperatures from the silica content of water from hot springs and wet-steam wells. American Journal of Science, 264(9), 685. doi:10.2475/ajs.264.9.685. Accessed on may 10th 2022.
13. Frau, F., Cidu, R., Ghiglieri, G., & Caddeo, G. A. (2020). Characterization of low-enthalpy geothermal resources and evaluation of potential contaminants. Rendiconti Lincei-Scienze Fisiche E Naturali. doi:10.1007/s12210-020-00950-6
14. Grant, M., & Bixley, P. (2011). Geothermal reservoir engineering second edition. In : Elsevier, 359p.
15. Hersir, G. P., Árnason, UNU-GTP, & LaGeo. (2009). Resistivity of rocks. 17-30.
16. Keller, G. V. (2017). Electrical properties of rocks and minerals. In Handbook of physical properties of rocks (pp. 217-294): CRC Press.
17. Keller, G. V. J. E. m. i. a. g. (1988). Rock and mineral properties. 1, 13-52.
18. Kumar, M., & Puri, A. (2012). A review of permissible limits of drinking water. Indian J Occup Environ Med, 16(1), 40-44. doi:10.4103/0019-5278.99696
19. Mpawenayo, B., Cocquyt, C., & Nindorera, A. (2005). Diatome (bacillariophyta) and other algae from the thermal springs of burundi (central africa) in relation to the physical and chemical characteristics of waters. Belgian Journal of Botany, 138(2), 152-164.
20. Ndyamuhaki, K., Ssembataya, O., & Balinga, J. (2021). Exploiting the Geothermal Potential of East Africa for Energy Diversification and Sustainability. 2021(1), 1-5. doi:https://doi.org/10.3997/2214-4609.2021605025
21. Ochieng, L. J. G. D. C., Nakuru Kenya. (2013). Overview of geothermal surface exploration methods.
22. Parkhomenko, E. J. R. o. G. (1982). Electrical resistivity of minerals and rocks at high temperature and pressure. 20(2), 193-218.
23. Patterson, J. R., Cardiff, M., & Feigl, K. L. (2020). Optimizing geothermal production in fractured rock reservoirs under uncertainty. Geothermics, 88, 101906. doi:https://doi.org/10.1016/j.geothermics.2020.101906
24. Sinzinkayo, J. M., Śliwa, T., & Wakana, F. (2015). Directions of Energy Balance Improvement in Burundi in the Aspect of Geothermal Energy Resources.
25. Tack, L. (1995). The Neoproterozoic Malagarazi supergroup of SE Burundi and its equivalent Bukoban System in NW Tanzania: a current review. Paper presented at the Annales-Museum Royal for Central Africa Series, in Vol 8 Geological Sciences.